I had some questions about - i will consider T1 input (new board design) for this purpose coneccted to any free RC channel , however all depends from freee space in chip .
For now this 16K small chip holding suprisly lot of informations , countings and functions but one timer is still free .

This parts are inductances - all can be 4,7 to 10uH - goot to add some inductances at both ENG input - also for all ADC inputs - this will help to cut noises from/to RC circuit .
If you need naked PCB , write me at PM or at remzibi1-AT-poczta.onet.pl

It is open hardware project under TAPR licence , so not copy and sale allowed - but for personal use no problem . Naked printed bards avaliable or ready devices as complete with(or without) GPS modules .
Software is not open source but all compiled files are avaliable , as firmware , font and config files and PC software (in fact all included in PC software).

Fortunate community of this OSD owners are growing and growing , including FPV flyers but not only , even some universitys and high schools for experimental use and other projects adaptations as well as some home designers .
So lastly I have many additional questions similat to like that :
I like to use OSD in another use -
on combant plane (with graphics and sigt to aim enemy) ,
on boat ,
on U-boat ,
on RC-car ,
on real car with recording ,
on bicykle ,
on motorbike as parameter monitor ,
on my Video monitoring system cooperate with PC ,
on my personal Videos information stamp ,
on Video as frames counter (whatever it means),
on my own top secret project , so can not tell you about ,
etc. etc. and many more .
I do not need to use GPS - I do not need it , I like the analog inputs use only - like Voltages , external sensors and possibly RPM meter .
OSD is cheapper without GPS .
So that is OK - here is the firmware for beta testing for everyones want it to test - working without GPS module at all .
All other advantages are remain without change .
Button work only as Video mode changer and save (something like save home) function saving Video mode and reseting timer at any moment .
Iviting logo will gone after 5 seconds so not any save needed for proper work .
So after firmware update all information regarding GPS data are not displayed .
Other like Timer , GMT date (will be zero so made it invisible) , GMT time (will be zero so made it invisible) , Frequency meter(RPM meter) , ADC , and graphical object are displayed without changes - all can be configurable (scaling , alarms etc.) in usual way using PC configuration program . Character editor and all rest - works in usual way .
Free UART(COM) port is set to default 38400 baud rate receiving and can be used to display on OSD layout absolutely everything we want or need to display at any location using external device - if we want to connect any .
Now for those programerrs who want to display anything using that port and their device .
So we can deliver information to display at location x,y looks like that :
[leading character][text message][ending character][ending space]
ending space is displayed always after mesasage.
String to OSD shoult look like that :
"$MXXYYLLEEabcd"
must be end by enter character CR LF linefeed and carriage return .
$M - means that it is meassage to display (M must be uppercase)
XX - is a x coordinate on screen , must be hex value
YY - is a y coordinate on screen
LL - is leading character hex value from font table
EE - is ending character hex value from font table
abcd - is a "text message" to dispalay
when LL or EE is Hx00 - then will be not displayed at all
when text message is "" [empty] then also will be not displayed
So string to OSD can belike that in C aduino sample
serial.println("$M050a4a4bI like that")
so at location x=05 y=10 will be displaed this :
<I like that>
as you see LL is 4a it means [<] char and EE is 4b it means [>] char .
or can be done like this way:
serial.print("$M") //header for message
serial.print("050a") //x and y coordinates
serial.print("4a4b") // leading and ending characters(graphics)
serial.println("I like that") //message with LR CR ends string
This is exactly how is working this function in OSD now .
As advantage of this system when we define most significant bit of XX coordinate for 1 then we choose small fonts for text message display (only capital letters) - when is 0 then default big letters are displayed from characters table capital and small letters .
XX |= (1<<7) // set 7 bit for small characters
XX &= ~(1<<7) //reset 7 bit for big characters
To be possible custom screen configuration , need of understanding how it is work .
The screen is divided on net where the charcters are writen .The grid is 30x16 with PAL mode nad 30x12 in NTSC mode .
Looks like that:
. X------>
Y 1 2 3 4 5 6 7 8 ... 29 30
: 2
: 3
: 4
v 5
. .
. 15
. 16
So when we made configuration we just teel the program where on the screen we want first character(or graphic) of our information - up left corner is coordinates X,Y (1,1) , bottom right corner is X ,Y (30,16) - remembre that NTSC mode Y must be no more than 12 .
How do we know what mode are currently in use ? - we will see after OSD init logo .
I hope that this firmware will help for many peaples doing his own project and will made poor man's OSD more open to world , also be more universal to variouse usage in many other project , not only flying platform .
-------
I foloowed of mmormota idea about add to OSD firmware ability to display any custom information delivered by RX input at the same baud rate with GPS module .
So if anyone have external device with GPS and retransmitiing GPRMC GPGGA messages , OSD can be used in usuall way - inluding autodetecting baud rate .
But also in middle of NMEA messages is possible to put custoom dispaly instruction - all described detaily in post above .
So here is the beta version of firmaware 1_60 - mostly for mmormota to test with ardupilot software .
It is working exactly as remzibi OSD (including GPS configuration commands sent at begining by TX line after baud rate detection) plus ability to display any custom oinformation delivered by UART(com port) in the middel of NMEA messages , format described in post above :
"$MXXYYLLEEabc"
So with this solution there are a bit solved problem of insufficient space in OSD's chip . maybe will be possible also displaynig artifical horizon and pitch using characters E0 to E7 from character-font table .
Here are some pictures of possible GPS connection with external device and OSD .

The chip is extremly well described in datasheet - in my unit first letters I was able to display literaly within 3 hours . Within two evenings all functions for display anything useful was ready .
I recommend to read datasheet - there are also explanations for some tips .

Better NOT . At first units was 5V provided but this done more problems than advantages - simply connect USB cable and connect to external battery OSD for supply , as the supply input(12V) is protected against opposite connection . 5V is not protected by any way , so any accident will cause of burned OSD unit - and this is what we do not want to experience .
So always use external battery for power-up OSD - USB cable use only for communication , not for supply .

There is almost ready software with additional ADCchannels - also for current sensor (any current sensor - possible calibration , even two way curerent sensors) - it will work independently from engine (main battery) voltage measurment .
Read some more here http://rc-cam.info/viewtopic.php?t=178 - there will be update with files when ready .
The main goal of that OSD was not occupy any RC channel - so it be possible to use with anyone even with very cheap 4 channel TX or 3ch (car) .
I do not plane to made any turn on -off function - but never say never .
instead of turn-on-off dispal - it is ability to arrange custom icons and information on screen most sweetable for any user needs .
By the way here is the II FPV meeting 2009 in Poland - here are briefly showed some of our harware "inventions" , and crash with clear picture untill ground hit .
http://vimeo.com/4675558
New LINK

I didn't expected but for some users reference I must also add the GPS picture with expalnation what side is UP what is BOTTOM .
Label is always bottom side , GPS must look the UP side to the sky looking for SATs .
I know that even in opposite side it can track 8 sats but better is to keep antenna looking in to the sky

You do not need clibing (faling) rate ? you can use it as graphic indicator like arrow up or down or graphic plus numeric value of climbing or falling rate . This climbing rate is working very accurate as the altidude drift is very slow and climbing rate is derivative - so accuracy almost like with air prassure sensor .
Anyway - it is absolutely your invetion how you like have screen layout done .